Platform lift



Nov. 8, 1966 H. c. JONES ETAL 3,283,350

PLATFORM LIFT Filed April 9, 1955 5 Sheets-Sheet 1 flamer G Jones BY fiend/a 2 Po #7 Pi 2 INVENTOR5 if/orneyi Nov. 8, 1966 H. c. JONES ETAL 3,283,850

PLATFORM LIFT Filed April 9, 1965 5 Sheets-Sheet 2 v' v z Home/"C Jbnes Dana/d 2 Poi/z 1966 H. c. JONES ETAL 3,283,850

PLATFORM LIFT Filed April 9, 1965 5 Sheets-Sheet 3 h INVENTOR5 Homer (I div/1:5 BY Dana/a 2 Poi/7 i/forney! Nov. 8, 1966 H. c. JONES ETAL 3,283,350

PLATFORM LIFT Filed April 9, 1965 5 Sheets-Sheet 4 FIG- 6 INVENTOR5 Homer 6', Jbnes BY Dana/d Z? Po/b 4/ for/my;

Nov. 8, 1966 c, JONES ETAL 3,283,850

PLATFORM LIFT Filed April 9, 1965 5 Sheets-Sheet 5 INVENTORS Homer CI fines BY Dana/d 2 ?ar/7 United States Patent 3,283,850 PLATFORM LIFT Homer C. Jones and Donald R. Roth, Sacramento, Calif.,

assignors of thirty-five percent to said Jones, twentyfive percent to said Roth, twenty percent to Carl C. Markwood, ten percent to Ronald L. Muenter and ten percent to Robert D. Hemenway, all of Sacramento,

Calif.

Filed Apr. 9, 1965, Ser. No. 447,043 3 Claims. (Cl. 1822) The invention relates to horizontal platform devices capable of supporting and lifting people or things, and, more especially, to devices of this nature which are mounted on vehicles.

The patent literature, as well as the market place, is replete with portable devices for raising and lowering a platform on which people and material are supported. In the main, however, such devices are complex and expensive and are not readily suited for use on the bed of a conventional motor vehicle, such as a pickup truck.

It is therefore an object of the invention to provide a platform lift which can easily be installed on the bed of any truck, such as a pickup truck.

It is another object of the invention to provide .a platform lift which can readily, accurately and safely be raised, lowered and stopped at any desired height.

It is still another object of the invention to provide a platform lift which is power driven, and which can be controlled by a person located on the platform.

It is a further object of the invention to provide a platform lift which is relatively economical to purchase and maintain, yet which is reliable in operation and long-lived. It is another object of the invention to provide a generally improved platform lift.

Other objects, together with the foregoing, are attained in the embodiments described in the following description and shown in the accompanying drawings in which:

FIGURE 1 is a side elevational view of the lift installed on the bed of a pickup truck, the lift being shown in lowermost position;

FIGURE 2 is a view comparable to that of FIGURE 1, but with the lift in an elevated position;

FIGURE 3 is a side elevational view of the lifting structure to an enlarged scale, showing the relative attitude of the components as lifting occurs;

FIGURE 4 is a rear elevational view to an enlarged scale, with the lift in lowermost position;

FIGURE 5 is a fragmentary sectional view to an enlarged scale, the plane of the section being indicated by the line 5-5 in FIGURE 3;

FIGURE 6 is a side elevational view of a modified form of device;

FIGURE 7 is a fragmentary side elevational view partially in section and to an enlarged scale, of the additional lifting structure provided in the modified form of device;

FIGURE 8 is a section on the line 8--8 in FIGURE 7; and,

FIGURE 9 is a section on the line 9-9 in FIGURE 7.

While the platform lift of the invention is susceptible of numerous physical embodiments, depending on the environment and requirements of use, substantial numbers of the herein shown and described embodiment have been made and used and all have performed in an eminently satisfactory manner.

The embodiment of the platform lift of the invention appearing in FIGURES 15, and generally designated by the reference numeral 12, is capable of use in a stationary location, but affords greatest utility on the bed 13 of a pickup truck 14. In this environment, the lift is most effectively used by persons, such as building contractors, tradesmen and farmers for elevating equipment, people and material, and for serving as a scaffolding under a variety of situations and locations.

Support is provided by a horizontal platform structure 16 including a generally rectangular, horizontal, bottom framework 17 having mounted thereon a floor 18 comprising, for example, a sheet of thick, sturdy plywood appropriately secured to the framework 17. For greater safety and rigidity, a handrail 19 is afforded, the rail 19 being strongly supported by pairs of vertical corner posts 21, braces 22, and inclined struts 23 and 24. A pair of lateral triangular brackets 26 (see FIGURE 4) mounted on the after corner post extensions 34 and secured at their tops by gussets 37 provide additional rigidity.

.For particular use in carrying and lifting materials, such as wallboard and pipes, there is provided a horizontal rack 31 including a plurality of conventional channel shapes and truss members 32 supported on a forward pair of upward platform corner extensions 33 and on the after pair 34 thereof. The forward portion 36 of the rack and attendant truss members extend over the truck cab, as appears most clearly in FIGURES l and 2, and thus afford an extensive supporting surface for elongated articles, such as pipes and ladders.

Elevation of the platform structure 16 from its lowermost position on the truck bed 13, as well as lowering thereof from an elevated position is accomplished by the controlled arcuate or swinging movement of a parallel motion mechanism 41, or linkage, connected to an hydraulic actuator 40.

The components of the entire platform lift device, except where specifically otherwise stated, are arranged in mirror symmetry about a vertical, median, longitudinal plane. Consequently, a description of the parts on one side will serve equally to identify the parts on the other side.

The parallel motion linkage 41 includes a pair of spaced, parallel lifting arms 42 and 43, each pivotally mounted, adjacent the forward end, on pivot pins 46 and 47, respectively. The pivot pins 46 and 47 are mounted on a vertical post 48 welded to a vertical frame beam 49 in face to face engagement therewith. The vertical members 48 and 49 thus form a strong vertical framework. In addition to being secured, at the bottom, to a horizontal frame 51 (see FIGURES 3 and 5) attached by fastenings 50 to the truck bed and chassis members (not shown), the vertical framework is further strengthened by a strut 52 and a lateral angle plate 53 mounted on the top surface 55 of the side walls 54 of the truck bed, as by a fastening 56. A top cross post 57 and a bottom cross beam 58 are further provided to increase strength.

The after ends of the lifting arms 42 and 43 are pivotally mounted on pivot pins 62 and 63, respectively, located on a vertical spacer member 64, or bar, attached to the brace 20 of the platform structure and extending vertically between the hand rail 19 and the horizontal floor supporting members 17.

The parallel motion mechanism 41 also includes a vertical central member 66 pivotally mounted on pins 67 and 68 located in upper and lower gusset plates 71 and 72, respectively, the gusset plates being secured to the corresponding upper and lower lifting arms 42 and 43 (see FIGURE 3).

As is also illustrated most clearly in FIGURE 3, wherein the platform lift is shown in successive positions, the parallel linkage arrangement 41 is effective to lift and lower the platform, while maintaining the floor 18 in a level attitude, between a lowermost position on the truck bed to an elevation above the bed.

The lifting, holding and lowering effort of the device is provided by the hydraulic actuator 40, previously referred to. The hydraulic actuator 40 .includes a hydraulic cylinder 76 pivot-ally mounted at its lower end on a pin 77 secured to a bracket 75 on the base fr-ame, and a plunger 73 (see FIGURE 2) pivotally mounted on a pin 79 located adjacent the upper end of the vertical link member 66, on a strong lateral bracket 81 (see FIGURE 4) mounted somewhat below the pivot pin 67 (see FIG- URE 3).

Projection of the plunger 78 is afforded by hydraulic pressure within'a hose 83 connected at one end to the bottom of the cylinder 76 and at the other end to a hydraulic pump, power driven by any appropriate mechanism, such as an electric motor connected to the trucks electrical system. The pump, the motor and the attendant fluid reservoir are conventional and are therefore not known in detail. Conveniently, these components are housed in a box 86 mounted on the forward part of the bed adjacent the cab (see FIGURE 4).

The hydraulic control valves are similarly conventional and are also preferably housed in the box 86. However, the valve control mechanism is located outside the housing, as appears most clearly in FIGURE 4, and includes a lever 87 appropriately connected adjacent its lower end to the hydraulic valve within the housing for up and down movement. A link 88 pivotally connects the upper end of the lever 87 to a transverse rod 89 journaled in a bearing 90 and a sleeve 91, the rod 89 being rotated by a crank arm 92 mounted on the outer end of the rod. If desired, the crank arm 92 can be moved by a cord 93, or other suitable actuator, so that the hydraulic control valve can be operated from a convenient location adjacent the side of the truck, or from the cab, or from the platform itself, when elevated.

The hydraulic control valve, as previously set forth, is of conventional make, and is preferably of the type that operates to provide pressure extending the plunger so long as the valve is held open by positive holding action on the cord 93. When the cord is slackened, the control valve quickly closes and the plunger remains in place. Lowering of the plunger is accomplished by opening a pressure release valve (not shown) of the kind commonly used on hydraulic valve mechanisms. The pressure release valve, when opened, allows the fluid to return to the reservoir at a metered rate, thus cushioning the downward movement of the platform. Preferably, the release valve is also remotely actuable, by any appropriate structure, as, for example, the crank arm 92 and attendant linkage, but with :a rigid rod in lieu of the cord 93 so as to provide a positive force on the crank arm in either direction of movement of the rod. The precise construction and mode of operation of the hydraulic valve mechanism forms no part of the present invention; however, the ability remotely to control the valves operation is of importance to achieve the optimum potential of the platform lift device.

In operation, the truck is maneuvered to the desired location and the brakes are set. The hydraulic system is turned on and the platform lift is ready for use. If one or more persons is to be lifted, the trucks tailgate is preferably lowered, for convenience, and the passengers climb onto the platform. Then, by suitable manipulation of the valve control mechanism, the platform is raised, in horizontal attitude, by extension of the plunger and movement of the lifting arms in a parallel motion fashion. Precise elevational positioning is afforded by suitable operation of the control valve mechanism readily accessible to a person located on the platform. Where only equipment or material is to be elevated, or where control is to be exercised from the ground, a duplicate set of controls adjacent the cab can readily be provided.

While the platform lift device shown in FIGURES 1-5, and heretofore described, enables people and objects to be elevated to a considerable height, it is sometimes desired to afford a sturdy platform capable of reaching an even greater elevation. In this situation, as is illus- 4 tratcd most clearly in FIGURES 6-9, a secondary lifting structure is afforded.

The underlying, or primary, structure comprises, in the main, the arrangement heretofore described and shown in FIGURES 1-5 and designated by the reference numeral16.

The forward portion 36 of the primary structure rack and truss is utilized as a support for the secondary structure, or auxiliary lift, generally designated by the reference numeral 101. The auxiliary lift 101 includes a pair of truss members 102 and 103 pivotally mounted at their forward ends on pins 104 and 105, respectively, on a stiffen-er or anchor plate 106 secured to an inclined beam 107 mounted on the forward portion of the horizontal rack 31 and the truss 32. A triangular stifiening structure, including a horizontal beam 111 and an inclined strut 112, further secures the secondary platform beam 107 and anchor plate 106 (see FIGURE 7). Additional security is provided by suitable fasteners 108 and 109, and angle plate 110.

Lifting and lowering of the secondary trusses 102 and 103 occurs by reason of an hydraulically actuated plunger 116 and cylinder 117, the plunger being pivotally mounted on a pin 118 attached to a thrust bar 120 secured to upper and lower pads 121 and 122 mounted on the respective truss members 102 and 103. The cylinder 117 is pivotally mounted on a pin 126 secured to a bracket 127 welded to the angle plate 110 (see FIGURE 7).

Adjacent the after ends of the trusses 102 and 103 there is provided a strong angle plate 131 to which the truss ends are pivotally connected, as by pins 132 and 133, respectively.

Suitably mounted, in a vertical attitude, on a pair of bracket arms 134 affixed to the angle plate 131, is a sleeve bearing 136 in which is journaled a vertical shaft 137 suitably lubricated by means of a fitting 138. At the upper end of the journal there is provided a thrust bearing 139 adapted to support a secondary platform structure 141 including a floor structure 142 and cage forming members 143.

Consistent with the endeavor, throughout, to place control of the entire apparatus in a location readily available to a person being lifted, a valve control lever 151, is conveniently mounted on a control panel 152 on one wall of the cage 143.

As appears most clearly in FIGURE 7, suitable hydraulic lines 156 connect the controls on the panel 152 and. the secondary cylinders 117. Further hydraulic lines and fittings, not shown, but of a conventional nature, are tied in to the primary energy source on the truck so that remote control of both lifting plat-forms is avail able to a person on the secondary platform at all times. If desired, additional power driven mechanism, readily available in the market place can be furnished to rotate the floor 142 and the cage unit 143 on the vertical axis of the shaft 137 so .as to afford the desired orientation.

This capability would be of especial advantage to a tree farmer, for example, who needs to change his location and orientation frequently to prune and trim the branches of trees in parallel spaced rows. In this type of situation, the passenger on the platform can remotely control his elevation and orientation while the driver of the pickup truck can advance or back up the vehicle on a signal from the passenger and can head the vehicle in a lateral direction, as desired, so as to bring the passenger into close proximity to the working area.

It can therefore be seen that we have provided a platform lift which is highly maneuverable, partially owing to the mobility of the supporting pickup truck, and which, furthermore, owing to its remote control capabilities, affords a device which is adaptable for use in meeting a wide variety of situations.

What is claimed is:

1. A platform lifting device for use on a pickup truck, said device comprising:

(a) a vertical fixed frame upstanding from the truck bed adjacent the cab;

(b) parallel linkage lifting arms pivotally mounted at their forward ends on said vertical fixed frame for vertical swinging movement between a first lower 5 position and a second elevated position;

(c) a horizontal platform framework pivotally mounted on the after ends of said parallel lifting arms, said platform framework being movable with said arms between said lower position and said elevated position, said horizontal platform being supported by the truck bed in said lower position and being vertically spaced therefrom in said elevated position, said platform being constrained by said parallel linkage arms to maintain a horizontal attitude between said positions;

(d) a horizontal rack mounted on and located above said platform in spaced parallel relation thereto, said rack including a first horizontal rack portion overlying said horizontal platform framework and a second horizontal rack portion extending forwardly from said rack portion and overlying the truck cab as said horizontal platform framework moves between said first position and said second position; and

(e) means connected to said vertical frame and to said arms for moving said arms, said platform and said rack between said positions.

2. A platform lifting device as in claim 1 wherein said moving means includes a hydraulically actuated mechanism, and wherein said mechanism includes means for remotely controlling the same.

3. The platform lifting device of claim 1 wherein said horizontal platform framework includes a rectangular base frame having substantially the same outline as the pickup truck bed, a plurality of vertical posts upstanding from the corners of said base frame, a pair of longitudinal handrails on opposite sides of said framework and connecting the tops of said corner posts on each opposite sides, and a pair of intermediate vertical bars on said opposite sides, each of said, bars extending vertically between said base frame and the corresponding one of said handrails, the after ends of said lifting arms being pivot-ally mounted on the upper and the lower ends of said bars.

References Cited by the Examiner UNITED STATES PATENTS 3,043,395 7/1962 Volkel 1822 3,132,718 5/1964 Pierce 1822 3,176,792 4/1965 Olson 182-2 FOREIGN PATENTS 515,449 2/ 1955 Italy.

REINALDO P. MACHADO, Primary Examiner. 

1. A PLATFORM LIFTING DEVICE FOR USE ON A PICKUP TRUCK, SAID DEVICE COMPRISING: (A) A VERTICAL FIXED FRAME UPSTANDING FROM THE TRUCK BED ADJACENT THE CAB; (B) PARALLEL LINKAGE LIFTING ARMS PIVOTALLY MOUNTED AT THEIR FORWARD END ON SAID VERTICAL FIXED FRAME FOR VERTICAL SWINGING MOVEMENT BETWEEN A FIRST LOWER POSITION AND A SECOND ELEVATED POSITION; (C) A HORIZONTAL PLATFORM FRAMEWORK PIVOTALLY MOUNTED ON THE AFTER ENDS OF SAID PARALLEL LIFTING ARMS, SAID PLATFORM FRAMEWORK BEING MOVABLE WITH SAID ARMS BETWEEN SAID LOWER POSITION AND SAID ELEVATED POSITION, SAID HORIZONTAL PLATFORM BEING SUPPORTED BY THE TRUCK BED IN SAID LOWER POSITION AND BEING VERTICALLY SPACED THEREFROM IN SAID ELEVATED POSITION, SAID PLATFORM BEING CONSTRAINED BY SAID PARALLEL LINKAGE ARMS TO MAINTAIN A HORIZONTAL ATTITUDE BETWEEN SAID POSITIONS; (D: A HORIZONTAL RACK MOUNTED ON AND LOCATED ABOVE SAID PLATFORM IN SPACED PARALLEL RELATION THERETO, SAID RACK INCLUDING A FIRST HORIZONTAL RACK PORTION OVERLYING SAID HORIZONTAL PLATFORM FRAMEWORK AND A SECOND HORIZONTAL RACK PORTION EXTENDING FORWARDLY FROM SAID RACK PORTION AND OVERLYING THE TRUCK CAB AS SAID HORIZONTAL PLATFORM FRAMEWORK MOVES BETWEEN SAID FIRST POSITION AND SAID SECOND POSITION; AND (E) MEANS CONNECTED TO SAID VERTICAL FRAME AND TO SAID ARMS FOR MOVING SAID ARMS, SAID PLATFORM AND SAID RACK BETWEEN SAID POSITIONS. 